1. Field of Invention
The present invention relates to a thermoplastic resin composition, and more specifically, to a thermoplastic resin composition having excellent flow properties comprising a crystalline thermoplastic resin as a continuous phase and a noncrystalline polyphenylene ether resin as a dispersed phase.
2. Description of Related Art
Crystalline thermoplastic resins such as polyamides, polyesters, and polyphenylene sulfides have several drawbacks including significant deformation in molding and insufficient heat resistance. Noncrystalline thermoplastic resins are often blended with crystalline thermoplastic resins to improve poor qualities in the crystalline thermoplastic resins. Noncrystalline thermoplastic polyphenylene ether resins that have high heat resistance are especially useful for blending with crystalline thermoplastic resins.
A resin composition of polyphenylene ether and polyamide is described in Japanese Laid-Open Application (kokai) No. Sho 56-16525, and a composition of polyphenylene ether and polyphenylene sulfide is described in Japanese Patent Publication (kokoku) No. Sho 56-34032. In addition, a resin composition of polyphenylene ether and polyester is described in Japanese Laid-Open Application (kokai) No. Sho 49-50050, and a resin composition of polyphenylene ether and polyolefin is described in Japanese Laid-Open Application (kokai) No. Sho 58-103557.
These blended resins have reduced flow properties compared to crystalline thermoplastic resins, although the polyphenylene ether resin does improve some properties in the blend. Further blending of a low molecular weight compound into these blends to improve flow properties generally lowers the heat resistance and degrades the mechanical properties of the blend.
In one investigation, a diamide compound was blended to improve the flow properties, as described in Japanese Laid-Open Application (kokai) No. Sho 60-44547. However, this resin composition had the drawback that the diamide compound bled from the bulk of the material to the surface.
Novel thermoplastic resins with improved paint adhesion strength were reported in U.S. Pat. No. 5,166,237. The resins disclosed were a polyphenylene ether, a polyamide, a polymer that improved paint adhesion, and a compatibilizer.
There has been a long-felt need to prepare novel thermoplastic compositions which have good flow properties, the ability to deform minimally during molding, excellent mechanical properties, oil resistance, and heat resistance.